The round terminal fixation structure mentioned above is used for example in an electrical junction box of an automobile (refer to Patent Literature 1). FIG. 11 is a perspective view showing a portion of an electrical junction box employing a conventional round terminal fixation structure. FIG. 12 illustrates an operation of fixing the round terminal to the bus bar shown in FIG. 11. FIG. 13 is a bottom view of the electrical junction box shown in FIG. 12. FIG. 14 illustrates a problem that arises in the round terminal fixation structure shown in FIG. 11. FIG. 15 is a side view of the round terminal fixation structure shown in FIG. 14.
As shown in FIGS. 11 and 12, a round terminal fixation structure 301 is configured to fix a round terminal 3 (also called a LA terminal) connected to an end of an electric wire 2 to a bus bar 304 provided to an electrical junction box 310 of an automobile in an overlapping fashion using a bolt 5.
In FIGS. 11-13, a reference sign 8 denotes a block made of synthetic resin. The bus bar 304, a nut 7 to which the bolt 5 is threadably mounted and a plurality of components such as a relay and a fuse (not shown) are attached to this block 8. A portion of the bus bar 304 is exposed at a terminal connection portion 80 of the block 8, and the round terminal 3 is placed on this exposed portion. In FIG. 11, an arrow B represents a rotation direction of the bolt 5 during threadably mounting the bolt 5 the nut 7.
The round terminal 3 includes a bolt insertion portion 31 provided with a first through-hole 30 through which the bolt 5 is passed (see FIG. 14), a core wire crimp portion 32 for crimping a core wire 21 of the electric wire 2, and an insulating cover crimp portion 33 for crimping an insulating cover 22 of the electric wire 2.
The bus bar 304 includes a flat plate portion 341 provided with a second through-hole 340 through which the bolt 5 is passed (see FIG. 14), a rotation restriction piece 342 extending perpendicularly from the flat plate portion 341 to restrict the rotation of the round terminal 3 when tightening the bolt 5, and a plurality of connection portions (not shown) electrically connected to the relay or the fuse.
As shown in FIG. 12, for such round terminal fixation structure 301, the round terminal 3 is inserted into the block 8 and placed onto the bus bar 304 at the terminal connection portion 80, and the bolt 5 having a washer 6 is passed through the first through-hole 30, the second through-hole 340 and the nut 7, and then the bolt 5 is rotated in the B direction (see FIG. 11) and threadably mounted on the nut 7, thereby fixing the round terminal 3 on the bus bar 304 and electrically connecting the round terminal 3 with the bus bar 304.